Devices and systems that use light emitting diodes (LEDs) may arrange the LEDs in strings. Some examples may include displays, computer monitors, automobile lighting and similar devices. To allow correct LED operation, a current or voltage regulator may provide power to more than one LED string. When the LED strings each have the same forward voltage drop, e.g. the LED strings may have the same number of LEDs on each string, a single voltage regulator may efficiently power multiple strings. However, efficiency can dramatically decrease for small forward voltages differences between different LED strings. Some techniques to efficiently drive different LED strings with different forward voltages may be bulky, expensive or both.